He bent forward while the signal was being read through to the suits, and tapped the rock close to their feet. “Here’s an example of what I was saying. I know there’s a good amount of ferromagnetics under us, just from the strength of the magnetic clamps in the suit. You couldn’t see that from the data we have on the ship, right? I don’t know what else we’ve got here, either. I’d hate to throw away a lump of platinum, just to make a hole setting for a drive.”

The two men moved slowly across the surface of the rock, examining each possible site carefully while Galley offered a running commentary on his selection logic. It took a long time, and almost four hours passed before Alexis Galley picked the last of the seven places that he wanted. He patiently answered Regulo’s continuous stream of questions.

“We don’t usually need to be this careful,” he said. “But this one’s an awkward shape — too long and thin.”

“You’re afraid it might start to tumble?”

“It has that tendency. The closer the shape of the rock to spherical, the less we have to worry about rotational instabilities. This one is almost twice as long as it is wide. We’ll be all right, though. With those drive placings, we’ll have no problem unless you find really big values for the boil-off mass. I’ll be interested to see what the temperatures run out here during perihelion fly-by. Up near the thousand mark, for my guess.”

The two men had begun to drift slowly back towards the Alberich. Regulo noted the easy control of small body movements and the tiny, almost unconscious use of the suit jets as Alexis Galley controlled his position and attitude. He did his best to mimic the older man’s actions.

“Fly-by will go really fast,” he said. “I don’t think we’ll spend more than two weeks inside the orbit of Mercury, in-bound and out-bound. The rock will get hot, but there’s no harm in that — and it won’t be for long.”

He turned his head and stared through the faceplate of the suit at the distant Sun. Still two hundred and fifty million miles away, it seemed small and strange, a dazzling, golden ornament in the black sky. Galley had stopped and was following his look.

“Come on, Darius,” he grunted. “You’ll be getting your belly-full of that in another month or two. Let’s get those calculations done and see to the drives. After that, you’ll have all the time in the world for Sun-watching. But I have to say, the sooner we get through with this whole thing and are in Earth orbit, the better I’ll be pleased.”

The drives set in the surface of the asteroid had finished their first spell of work long ago. Now they sat idle. They would not be needed again until the time came to decelerate into Earth orbit. The Alberich, still tethered to the rock, was falling with it, steadily and ever faster, toward the Sun. They were past Venus, past Mercury, plunging to perihelion. Darius Regulo, magnetic clamps holding him firmly to the surface of the planetoid, paused in his work to take a quick look at the solar primary. It had swollen steadily since they left the Asteroid Belt. Now it was ten times its former size and dominated the sky.

“Come on, move it.” Nita’s voice came suddenly over the suit phone. She must have been watching on the external viewing screen. “Don’t hang about out there. We’ll be separating the Alberich from the asteroid in less than two hours.”

“On our way,” Regulo said. “I just finished checking the last drive. They’ve all come through first impulse well. Unless Alexis disagrees with some of my data, I don’t see a reason to change any of the settings before we use them again.” He looked closely at the rock surface beneath his feet. “I’d say we’re getting about our predicted amount of boil-off from the surface here.”

“And it’s getting hotter than hell.” That was Galley’s voice, grumbling over the suit circuit. He was standing on the rock, close to the tether point that connected the Alberich to the asteroid. “I’m showing contact temperatures of over five hundred Kelvins, going up every minute. Come on, Darius, put the lid on it and let’s get out of here.”

“I’ll be right with you.” Regulo bent to clamp the protective cover over the last of the drive units. It was a little tricky getting the fit to the asteroid’s rough surface. He crouched lower, frowning at the awkward bolts.

He was carefully turning the last coupling when the tremor came. His attention was all on the clamp and he saw nothing — but the rock surface was suddenly shaking beneath his feet. Even as he felt the vibration, he knew that it was impossible. Earthquakes simply don’t happen on tiny rock fragments only a couple of kilometers across.

He straightened, and at the same moment there was a long, metallic screech over his suit phone. The Sun, which a moment ago had been shining in fiercely through his faceplate, was abruptly darkened by an obscuring cloud. He looked for the Alberich but it too had vanished within a glowing white nimbus.

“Alexis! What’s going on?”

He waited. There was no reply over his phone. After a few seconds he saw the shape of the ship, appearing mysteriously through the fog. The fog. There could be no fog here, far from any possible form of atmosphere. Regulo set his course for the ship, using his jets as Alexis Galley had taught him. As he moved, his eyes scanned the surface of the rock looking for Galley himself. The other man had to be somewhere on the asteroid. There was no sign of him, but before Regulo was halfway to the ship tether point he was beginning to see a slight change to the familiar shape of the surface. Where he had last seen Galley there now stood a deep pit, gouged into the rock itself. A fuming gas, brightly lit by the glaring beams of the swollen Sun, was pouring out of its interior.

The Alberich was still attached to the rock by its tether. Regulo propelled himself up to it and looked in dismay at the condition of the ship. The forward hull plates had been shattered, with a great boulder of dark rock embedded in the wall of the main cabin. He looked in through a broken port and saw Nita Lubin’s body, unsuited, floating free against an inner bulkhead.

Even while his mind was struggling to accept the reality of an impossible series of events, some deep faculty was coolly assessing all that he saw and seeking explanations. He looked for an instant at the face of the Sun. The photo-sensitive faceplate of the suit darkened immediately, so that he could see nothing in the whole universe but that broad and burning face. The Alberich and its cargo were still falling towards it at better than thirty miles a second.

What were the last words he had heard from Alexis Galley? …over five hundred Kelvins, going up every minute. Somehow, that had to be the key. A hundred and thirty degrees above the boiling point of water, almost four hundred degrees above the boiling point of methane. The surface of the asteroid had been cooking hotter and hotter in that unrelenting Sun, vaporizing the volatiles beneath. The pressure of the trapped gases forming there had increased and increased… until at last some critical value had been reached. Part of the rock had fractured under the intolerable stress. Fragments had been propelled out by the expanding gases, into the body of Alexis Galley, into the hanging target of the Alberich. All that had saved Regulo had been luck, his position on the asteroid and distance from the explosion.

But saved for what? Regulo looked about him with a sickening realization of his own plight. The ship was a total wreck, he had known that as soon as he saw it. There was no way that it could be powered up to take him away to a safe orbit. The automatic alarm system should have triggered as soon as the ship’s internal condition became unable to support human life. Regulo tuned quickly to the distress frequencies and heard the electronic scream as the ship blared and roared its high-frequency Mayday across the System. The signal would already be activating the monitors far out beyond Mercury, but that would be of no use to him. When the ship had swung past the Sun and out to the cooler regions of the Inner System, others would come and recover the hulk and its valuable cargo. But that would be too late for Regulo. At the moment, the Alberich was as unreachable by outside assistance as if it were sitting on the blinding photosphere of the Sun itself.